Characteristics of Tide Variation/Change Along the China Coast
- Jianli Zhang (National Marine Data & Information Service) | Hui Wang (National Marine Data & Information Service) | Wenjing Fan (National Marine Data & Information Service) | Wenshan Li (National Marine Data & Information Service) | Tong Gao (National Marine Data & Information Service) | Qiulin Liu (National Marine Data & Information Service)
- Document ID
- International Society of Offshore and Polar Engineers
- The 28th International Ocean and Polar Engineering Conference, 10-15 June, Sapporo, Japan
- Publication Date
- Document Type
- Conference Paper
- 2018. International Society of Offshore and Polar Engineers
- mean high tide level, trend, mean tidal range, mean sea level, mean low tide level
- 0 in the last 30 days
- 12 since 2007
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Based on the observing data from 1980 to 2016 of 24 tide gauges, the long term tide variation/change along the China coast are investigated. Results show that the mean sea levels, M2 constituent amplitudes, mean tidal ranges, mean high tide levels, mean low tide levels along the China coast show rising trends, at the average rate of 0.32 cm/year, 0.09 cm/year, 0.31 cm/year, 0.51 cm/year, 0.19 cm/year, respectively. From the northern Yellow Sea to Hangzhou Bay, the mean tidal ranges increase significantly, with the values of 0.50-1.30 cm/year. The mean tidal ranges along China coast have obvious 18.61 year cycle variation, which the amplitude is more than 20 cm on the Beibu Gulf coast.
In the last hundred years, the global climate is experiencing the change with a main characteristic of warming. It is pointed out in the fifth IPCC (2013) that the global mean surface temperature rising rate is about 0.012 °C /year during 1951-2012, and during 1971-2010, the global mean sea level has been rising at a rate of about 0.02 cm/year caused by the thermal expansion of sea water, the melting of land glaciers and polar ice sheets. Sea level rise can increase the frequency and effects of occurrence of storm surge, flooding, erosion, salinization and inundation of low-lying land in coastal areas (Chen, 1997).
The variation and reduction of the effect the seabed and lateral friction in the shelf shallow water regions caused by global sea level rise lead to the change of the propagation of the incident wave, the reflected wave and the refraction wave, and the shift of the amphidromic point (Zhang, 2000). The possible effects of sea level rise on the tidal wave system in the China Sea are studied by means of the numerical methods (Yu, 2008; Yan 2010; and Zhang, 2013). Assuming the sea level rises 100cm, it is found that the highest astronomical tidal level is up to 10-16cm, and the depth datum of the sea chart drops to 10-12cm in the China Sea (Yu, 2007). The M2 and K1 constituent amplitude in the eastern Pacific has a long-term increasing trend, and the variations of the M2 and K1 component amplitude at all tidal stations in the north of 18°N are consistent (Jay, 2009). The linear changes of the major tidal constituents are commonplace around the world, although not necessarily with large spatial scales (Woodworth, 2010). The S2 was found to be the component that usually shows the largest linear changes among the main tidal constituents in the east Pacific (Müller, 2011). During 1954-2012 years, the semidiurnal tidal parameters show significant secular trends in the Bohai, Yellow Sea and Taiwan Strait, and the largest increase for M2 amplitude is found by 0.4-0.7 cm/year in the Yellow Sea (Feng, 2014). In the northern part of the South China Sea, the amplitude and phase of O1, K1 and M2 has significant periodic variation, and the amplitude of S2 is more stable (Fu, 2015).
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